Motion amplifier for condition responsive gauge instrument

ABSTRACT

Amplifier apparatus for providing output motion correlated to condition change motion or deflection of a condition responsive element. The amplifier in a preferred embodiment is mounted onto the condition responsive element for floating conjoint movement therewith. A remotely connected actuator, extending into the motion path, defines a pivot axis for a hinged gear sector arm of the amplifier. In pivoting about the actuator axis, the sector arm operably drives a rotatable output shaft supporting a pointer or the like.

This application is a divisional of application Ser. No. 413,483 filedNov. 7, 1973, now abandoned, which was a continuation-in-part ofapplication Ser. No. 186,120 filed Oct. 4, 1971, now abandoned.

BACKGROUND OF THE INVENTION

1. The field of art to which the invention pertains includes the art ofmeasuring and testing as applicable to amplifier movements for gaugeinstruments.

2. Amplifier movements for use with pressure gauges, temperatures gaugesor the like are well known and have been used commercially for manyyears. Typically, such gauges have a condition responsive element suchas a bellows, Bourdon tube, bi-metal coil or the like providing adisplacement in response to condition changes to which the element issensitive. In a common construction, the amplifier or "movement" iscomprised of leverage and gearing operably responsive to arcuatedeflective motion of the element for driving an output shaft supportinga pointer movable relative to a fixed dial plate. The dial registrationopposite the pointer position is indicative of the condition state suchas pressure or temperature with which the instrument is being operative.

Traditionally, such prior amplifiers or movements include variouselements of sturdy construction which are fixed or anchored relative tothe motion path of the element. It is usual for the pointer shaft andone or more of the intermediate components to be operated about such anaxis. Performance of those gauge constructions are capable of providinghigh levels of readout accuracy and have therefore been generallyregarded as satisfactory. Notwithstanding their general acceptability,they are marketed on a highly competitive basis such that theirmaufacturing costs largely dictate ultimate consumer price andconsequent profit.

Contributing significantly toward those costs are several factors notleast of which is the construction mass per se of the componentsassociated with the prior art type stationary movements requiring fixedposts, plates or the like to which the anchored axes components can besecured. In addition, such units are characteristically regarded ascomplex and difficult to calibrate because of the different adjustmentsettings, each of which mutually affect each other. It is not unknownfor many man hours to be consumed in obtaining final calibration inorder to meet the expected operating standards of the instrument. Yetanother high cost factor has been the need for a relatively expensivehair spring or the like employed to minimize or overcome slack betweencomponents that might otherwise arise to adversely affect operation andaccuracy. Moreover, by virtue of their constructions, it has beenimpractical if not impossible to obtain effective temperaturecompensation for maintaining instrument accuracy throughout widetemperature ranges to which it is subjected. The latter is generallyattributable to utilization of a temperature sensitive link as part ofthe movement located within the case concealed or otherwise unresponsiveto environmental changes occurring elsewhere. Despite recognition ofthese inherent drawbacks, the prior stationary type movements havecontinued heretofore to be employed as the industry standard for lack ofa suitable alternative. Exemplifying movements of the prior art arethose disclosed in U.S. Pat. Nos. 3,214,979; 1,658,840 and 1,584,742.

SUMMARY

This invention relates to novel apparatus for amplifying motion of acondition responsive element to drive an output shaft supporting indiciamechanism such as a pointer. More specifically, the invention relates tosuch an amplifier apparatus or movement of comparatively lowerconstruction cost than similar purpose movements of the prior art. In apreferred embodiment, the operating components including the pointershaft are mounted directly onto the displacing free end of the conditionresponsive element for conjoint floating movement therewith. By virtueof this construction the previously required extra mass and attendantexpense is substantially if not completely eleminated. At the same timecalibration, as compared to previous techniques, is substantiallysimplified since each adjustment setting canbe independently renderedwithout affecting the others. Moreover, the arrangement of componentsplaces them in a weighted relation to each other enabling elemination ofthe formerly required slack removing hair spring. Where temperaturecompensation is desired, the construction lends itself to increasinglyeffective sensitively by means of a compensating element operablypositioned with thermal contact both inside and outside of the casing asto substantially enhance the operable reliability of such compensation.

In accordance with the invention, the amplifier hereof is comprised of aone piece low cost support frame which can attach directly to the freeend of a motion producing condition responsive element with which it isto be used, e.g., a Bourdon tube which operates arcuately. A gearedsector arm is hinge connected to the frame while a remotely supportedbut stationary actuator link intersects the arm at a predeterminedlocation displaced from its hinge to define a pivot axis therefor. Thegeared end of the sector arm meshes with a pinion on a rotatable pointershaft also supported on the frame at a location substantially coincidentwith the axial center of the gauge dial. In response to conditionchanges, induced displacement or motion of the condition responsiveelement results in a like motion to the amplifier moving it rotationallyabout the element's natural pivot point. The latter movement causespivoting of the sector arm about the actuator axis relative to theremaining components to in turn rotatably drive the pointer shaft anamount correlated to the displaced motion of the element.

It is therefore an object of the invention to provide novel amplifierapparatus for transmitting motion of a condition responsive element toan output drive shaft.

It is a further object of the invention to provide a novel apparatus formotion amplification as in the previous object that is capable of beingdirectly attached to the condition responsive element for conjointfloating movement therewith.

It is a further object of the invention to provide a gauge instrumenthaving a novel motion amplifier of substantially less mass and cost thansuch similar purpose movements of the prior art.

It is a still further object of the invention to provide a gaugeinstrument as in the last recited object in which the gauge calibrationprocedure is substantially less complex than previously required forsuch similar purpose movements of the prior art.

It is yet another object of the invention to provide a gauge instrumentwith a novel amplifier apparatus enabling temperature compensationincreasingly sensitive to environmental conditions than such similarpurpose compensation construction previously available.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are framentary front and end elevations respectively of apressure gauge embodying the motion amplifier hereof;

FIGS. 3 and 4 are enlarged front and end view respectively of the motionamplifier;

FIG. 5 is a motion diagram for the gauge components of FIG. 1;

FIGS. 6 and 7 are fragmentary front and end elevations, respectively, ofa first optional variation for effecting span adjustment;

FIGS. 8, 9 and 10 are front elevations of alternative second optionalvariations for effecting zero adjustment;

FIG. 11 is a diagrammatic view illustrating a preferred technique foraccurately effecting zero adjustment;

FIG. 12 is a fragmentary view of a combined structure for effecting bothspan and zero adjustment;

FIG. 13 is a sectional view taken substantially along the lines 13--13of FIG. 12;

FIGS. 14 and 15 are fragmentary front and end elevations, respectively,of a third optional variation for effecting both temperaturecompensation and span adjustment;

FIG. 16 is a fragmentary front elevation of a variation to the span andadjustment features of FIGS. 14 and 15 for also enabling zeroadjustment;

FIGS. 17 and 18 are sectional views, respectively, taken substantiallyalong the lines 17--17 and 18--18 of FIG. 14;

FIGS. 19-22 are partial front elevations of a different embodiment ofgauge instruments incorporating the motion amplifier hereof;

FIG. 23 is a fragmentary front elevation of a modified form of amplifierfor the foregoing instrument embodiments; and

FIG. 24 is a fragmentary front elevation of an instrument embodimentutilizing the amplifier hereof in its inverted relation.

For an understanding of the invention, reference is now made to thedrawings and particularly to FIGS. 1 and 2 in which there is illustratedan exemplary use of the amplifier designated 10 in conjunction with anotherwise conventional pressure gauge instrument designated 11. Theinstrument includes a stem or socket 12 in which fluid pressure to besensed is received at an inlet 13 and includes threads 14 for connectingthe gauge to a system with which it is to be employed. Fluid pressurereceived at inlet 13 is communicated to a Bourdon tube 18 that issubject to arcuate motion displacement in a well known manner inresponse to incremental pressure changes received at inlet 13.

The motion of Bourdon tube 18 is conducted to amplifier 10, as will bedescribed below, to produce an amplified and correlated motion foroperatinga pointer 19 relative to pressure values 20 on dial face 21.Except for stem 12, each of the foregoing components comprise theoperating mechanism that is substantially contained within enclosedhousing 24. The housing consists of a cup-shaped, shell-like backing 25secured via screws 26 to stem 12 and a bezel 27 telescopically fit ontobacking 25 to secure a crystal 28 for viewing the pointer positionrelative to dial values 20.

With reference also to FIGS. 3, 4 and 5 the amplifier 10 hereof will nowbe described in a first embodiment as utilized in the pressure gauge ofFIGS. 1 and 2. Comprising the amplifier is a centrally upright U-shapedcarriage or frame 32 integrally formed to include symetrically spacedapart side legs 33 and 34. Frame 32 is preferably of a hard metal suchas brass and of relatively thin cross section to enable slight spreadingof its side legs by flexing or bending for reasons as will beunderstood. Supporting the frame is a tang 73 of an intervening bracket35 which in turn is U-shaped at its other end for receiving the free endof Bourdon tube 18. Bracket 35 is permanently secured to the Bourdontube at 36 as by welding, soldering, brazing or the like. Being securedin this arrangement, the carriage and components that it supports aresubject to a floating movement conjointly with deflection of Bourdontube 18 as a result of pressure changes received at inlet 13.

Installed between carriages legs 33 and 34 by spreading the legs asaforesaid, are a pair of longitudinally displaced rotatable shafts 39and 40. In this manner aligned apertures in the opposite legs providejournalled support for the transverse shafts by a snap-in installationwithout the need for separate bearings or bearing materials. Shaft 39provides a hinge support for a geared sector arm 41 secured thereto asby staking at 44 while shaft 40 represents the output drive shaftsupporting pointer 19. For purposes of symetry, the axis of shaft 40 islocated to substantially coincide with the central axis of dial plate21. Rotation of shaft 40 for positioning pointer 19 is effected by apinion 46 secured thereto and meshing with sector gearing 47 of arm 41.As thus far described, all components of the amplifier assembly aresecured by bracket 35 to the end of Bourdon tube 18 for conjointfloating movement therewith.

For operating the amplifier there is provided an actuator in the form ofa relatively rigid sheet metal pin or link 50 of predetermined fixedlength remotely supported and anchored to a suitable location elsewhereabout the instrument. As will be understood, actuator 50 can be anchoredor secured to any convenient stationary structure about the instrument.In a preferred construction for the embodiment being disclosed there isprovided in the wall of stem12 a vertically slitted recess 53 inwardlydished at 54 to receive the looped end 55 of actuator 50. Supportingthat end of the actuator in a pivoting relation is the outboard end 56of screw 26. Opposite end 57 is likewise looped to receive screw 58 forconnecting arm 50 to the sector arm through aperture 51 locatedintermediate shafts 39 and 40. In this manner, actuator 50 provides apivot axis for sector arm 41 defined about aperture 51 for reasons aswill be understood from the discussion below. In the intended sense,actuator line 50 is not per se a component of amplifier 10 but insteadprovides the cooperative operating mechanism thereof in response to itsfloating motion with the free end of Bourdon tube 18.

For an understanding of these operating relationships reference is alsomade to FIG. 5 in which the arcuate deflection motion of Bourdon tube 18about its natural pivot axis 60 is represented by arrow 61. The lattermotion produces a like motion of amplifier 10 relative to fixed pivotaxis 51 affecting shaft 39 as indicated by arrow 62 and affecting shaft40 as indicated by arrow 63. The travel extent represented by thedifferent arrows 61, 62 and 63 is of course a correlated function of theexact geometric arrangements between the respective components and theirrelationship to pivot axis 60. At the same time travel 61 is related ina well known manner to the structural properties of condition responsiveelement 18 and the operational ranges to which it is to be subjected.

Whatever travel extent is incurred by shaft 39, as represented by arrow62, the effect is to produce a hinged motion of sector arm 41 thereatbeing pivoted about axis 51. This in turn results in a meshed drivebetween sector gearing 47 and pinion 46 for operably rotating pointershaft 40 while the latter is concomitantly displaced from the dial axisto an extent defined by arrow 63. To accommodate axial displacement ofshaft 40, dial 21 includes a central aperture 64 of sufficient diametralclearance so as not to interfere with the operation. Since deviation ordisplacement within aperture 64 is relatively minimal, it is hardlyperceptible to the eye except on close inspection and is notobjectionable because of its close visual simulation to otherwiseconventional prior art operation when viewing the dial from afar. By wayof example, for a two inch pressure gauge operationally adapted forpressures from zero to 100 psig, full tip travel of the Bourdon tube isapproximately 0.100 inches producing a motion displacement 62 of shaft39 of about 0.095 inches to in turn produce a motion displacement 63 ofshaft 40 of about 0.030 inches equal to about 1/32 inches.

A second amplifier embodiment in the form of a variation from theforegoing will now be described with additional reference to FIGS. 6 and7 disclosing structure readily enabling "span" adjustment of theinstrument. As known in the art, this adjustment is for effectingpointer travel coincident with the dial span encountered by theinstrument on being subject to a full range of pressures through whichit is intended to operate. For these purposes, actuator 50 extendsincreasingly downward in stem recess 53 to just above threads 14 whereit is securely staked to the stem at 66. Preferably recess 53 throughoutits vertical extent is of a width only slightly greater than that ofactuator 50 and the latter is offset at 67 to prevent inadvertentsidewise rotation within the recess. From above offset 67, actuator 50bends inwardly of the dished recess area 54 whereby its side edge 65bends engagingly against conical nose 68 of a set screw 69 threadablyadjustable within stem 12. Vertically beyond that location the actuatorextends upwardly to an offset bend or crank 52 received within elongatedslot 71 of sector arm 41 for defining the pivot axis therefor. Actuatoroffset 72 extends in interfering relation to the pivot path of arm 41for providing an overload stop in the event of an overpressure suppliedto the gauge. Similarly tang 73 of bracket 35 acts as an underload stop.

Pivoting leverage is essentially a function of the displacement or spandistance represented by the dimension "X" (FIG. 6) between the pivotaxis at 52 and the axis of shaft 39. By virtue of actuator 50 being bentin spring-like engagement against conical nose 68, set screw adjustmentinwardly or outwardly of the stem causes actuator 50 to be shiftedarcuately as represented by arrows 70. Whether shifted right or left, asviewed in FIG. 6, the operating effect of screw 69 is to alter dimension"X" for shifting location of the pivot axis. In this manner the pivotaxis can be relocated until span setting for desired accuracy of theinstrument is obtained. Reducing dimension "X" has the effect ofincreasing the amplification ratio and vice versa. The longitudinalshape of slot 71 for these purposes substantially corresponds with theshifting motion path of actuator 50 represented by arrows 70. In thisinstance slot 71 is arcuate of radius generally corresponding to theactuator length.

A third amplifier embodiment in the form of further variations of theamplifier in order to enable zero adjustment is specifically illustratedin FIGS. 8-11. This adjustment, as is understood in the art, is forobtaining coincident registration between the pointer position and thedial value 20 corresponding to the pressure value to which theinstrument is being subjected. In accordance herewith, operating atfifty percent of rated capacity should place pivot axis 52 in a straightline between tube axis 60 and hinge axis 39 in the manner illustrated inFIG. 11. By this means, it is only necessary in accordance with apreferred technique to pressurize the instrument to fifty percent of itsoperating value at which time pointer 19 should register opposite thatcorresponding value 20 on dial plate 21.

To achieve adjustment in the manner of FIG. 8 for effecting the lattercorrespondence, segment arm 41 includes a cutout 74 containing a centralcantilevered island portion 75 connected to the main body portion by athin tang 76. By means of screwdriver slots 77 and 78, insertion of ascrewdriver enables rotating central portion 75 about tang 76 until theproper pointer setting is obtained. In FIG. 9 the principle of zerosetting is similar except that central portion 75 is commonly securedseparately on axis 39, as by a spring load or press fit (not shown).This permits relative angular displacement between 75 and 41 which canbe varied by a screwdriver in a manner similar to that previouslydescribed. In FIG. 10 the operating length of actuator 50 is directlyadjustable. A short length 80 slideable relative to the main body ofactuator 50 engages spaced apart guide links 81 and 82 and by means ofan eccentric or other suitable type adjustment 83 links 81 and 82 can bemoved closer together or further apart as required to effect zeroadjustment.

As illustrated in FIGS. 12 and 12 there is disclosed structure enablingdial front setting of the zero adjustment with a factory settable spanadjustment. For effecting the latter, there is provided an adjustablesegment arm 84 arranged to extend contiguously parallel to sector arm41. Included at one end of segment arm 84 is a staked pin 88 laterallyextending through actuator 50 and sector slot 71 to define the pivotaxis for sector arm 41. Centrally longitudinal within segment arm 84 isan elongated slot 89 of generally force fit dimension with respect ao anannular hub 90 on hinge shaft 39. A larger outer hub 91 maintains arm 84closely juxtaposed to arm 41. By forcing arm 84 frictionally in eitherdirection past hub 90 whereby to relocate pin 88 closer or furtherdisplaced relative to hinge shaft 39, dimension "X" is varied untilproper span adjustment is achieved. To effect zero adjustment actuator50 is secured to stem 12 in the manner of FIG. 1. However, unlike theprevious description thereof, supporting screw end 56 is eccentricrelative to its threading axis such that rotation of screw 26 shifts thesupport of end 55 in the manner of arrow 92. Since screw 26 isaccessible from exterior of case 24, on site zero field adjustments canbe readily made without disassembly of the unit.

In order to obtain temperature compensation in accordance with furthervariations hereof, reference is now made to FIGS. 14-18 in whichactuator 50 is comprised of a bi-metallic element sensitive totemperature change to which it is exposed. To appreciate the simplicityand yet effectiveness of the structure herein the thermal factorsnormally affecting gauges of this type should be understood.

These factors are interrelated and generally consist of "thermalbalance" and "thermal stress". The former represents a condition whichexists when the various operating components are all at the sametemperature. Preferably, calibration of the instrument should beconducted under thermally balanced conditions. Thermal stress isgenerally associated with variations in thermal expansion coefficientsbetween different components. The different temperatures to which thevarious components are subjected act in the course of temperature changeto impose undesirable stresses and changes in setting of the instrument.It should be appreciated that thermal balance is not normally duplicatedin industrial use applications for such instruments as all componentsare rarely at the same operating temperature. For example, the stem isfrequently inserted into a pipe well or the like at a substantiallydifferent temperature than the ambient environment into which thehousing extends for visual reading. Even temperature swings in theambient environment produce temperature gradients between the inside andoutside of the housing that equalize or become eliminated only after anextensive time lag. Consequently, because of these temperaturedifferences and resulting gradients, the operating components aresubject to constantly varying thermal stresses which differ throughoutthe instrument. Most significant of these stresses, from a practicalpoint of view, because of their relative permanency and magnitude, arethe temperature differences likely to be imposed in service on stem 12in contrast to that imposed by the ambient conditions surroundinghousing 24. It is not uncommon, for example, on steam applications orthe like for stem 12 to be at 200° F. variance with the remainder of theunit to which the stem heat is transmitted by conduction. Moreover, suchtemperature error is negligible at zero gauge pressure but is known toincrease thereafter and become maximum at 100% gauge pressure.

In accordance herewith, bi-metallic actuator 50 of FIGS. 14-18 is doublestaked in stem 12 at 66 similarly as described in connection with FIG. 6affording the actuator a common parallel thermal source with Bourdontube 18. In order not to affect pointer zero, actuator cross-sectiongenerally below offset 94 has a lengthwise ridge 93 (FIG. 17) whichrenders that longitudinal portion thermally stiff while the uppercross-section, approximately above offset 94, is generally rectangularand flat as shown in FIG. 18 affording it increased thermal activity.With this arrangement, set screw 69 having a tapered seat 68 can beutilized as before for effecting a span adjustment by rotating theactuator in the manner of arrow 70 about its staked portion 66, On theother hand, the upper portion being more thermally active will similarlybend about screw 69 in response to temperature change to which it issubjected to essentially change the span or amplification ratio withtemperature. By such changes thermally induced by the actuator, thepivot axis is relocated along a path which is neutral when the gauge andtherefore segment slot 71 is at its zero position. In response to atemperature increase, crank pin 52 is displaced away from hinge shaft 39to increase dimension "X" for effecting amplification reduction and viceversa. When desired to likewise obtain temperature compensated zeroadjustment, the construction of FIG. 16 can be employed which includesthe added feature of a thermal expansion loop 95. Expansion andcontraction of loop 95 in response to temperature change produces anessentially linear movement of the actuator to effect changes in zerosetting similarly as hereinbefore described.

With this construction, unlike that of the prior art, the temperaturecompensator is directly attached to the gauge stem for simultaneous andparallel conduction of temperature changes to the compensator and to theBourdon tube. Moreover, by virtue of Bourdon tube 18 and the compensator50 having matched cross sections (thermal resistance) they producesimultaneous motion of arm 41 and pivot 52 in response to temperaturechanges. Thus, maximum correlation can be obtained in the quickestpossible time between thermal effects and thermal compensation sought tobe achieved.

Referring now to FIG. 19, there is shown another type of gaugeinstrument utilizing amplifier 10 hereof. As constructed, the instrumentincludes two Bourdon tubes 98 and 99 operating as a pressure gauge inwhich a common pressure is received via stem 12 to produce opposingmovement in each of the tubes. This construction can be used, forexample, in situations requiring high vibration or shock resistance.Alternatively, the unit can be operated as a differential pressure gaugein which each of the Bourdon tubes are connected to a different sourceof pressure via separate stems 12. In either event, the amplifier issecured to the movable free end of Bourdon tube 98 with which it issubject to conjoint floating movement similarly as before. Actuator 50is secured to the free end of Bourdon tub 99 to effectively enjoyconjoint floating movement with the latter whereby relative motiontherebetween produces a hinged motion of gear sector 47 about hinge axis39. Similarly as before, the hinged motion effects pivoting of gearsector arm 41 about pivot 52 for driving pinion 46 and pointer shaft 40.

FIGS. 20-22 represent additional types of gauge instruments utilizingamplifier 10 hereof. In these instrument embodiments, unlike thosepreviously described, their condition responsive elements incursubstantial linear rather than arcuate displacement in response tocondition changes of their sensitivity. In FIG. 20, amplifier 10 issupported on a triple radius Bourdon tube 101 for substantially linearmovement as shown by arrow 102. Tube 101 may, for example, be of a typedisclosed in U.S. Pat. No. 2,741,129, The constructions of FIGS. 21 and22 similarly produce substantially linear movement by means of a bellows103 secured to a base 104 and a piston 107 operable within a cylinder108, respectively.

FIG. 23 illustrates a modified form of amplifier 10 in which thelocation of the hinge shaft and pivot axis of actuator 50 areinterchanged with respect to shaft 40 and are here designed 39' and 52',respectively. Axis 52' is displaceable for span adjustment in slot 71'by means of set screw 69 similarly as before. It has been found thatthis arrangement, in contrast with the prior arrangement, can morereadily be used to eliminate sine wave error that might otherwise beencountered in the courseof gauge operation.

FIG. 24 represents a still further embodiment in which the support ofamplifier 10 and actuator 50 are inverted and interchanged with respectto base 12 and the tip of Bourdon tube 18. In this arrangement, frame 32of amplifier 10 is secured to the offset termination 109 of a rigid pinor link 110 staked at 66 and laterally displaceable by adjustable setscrew 69. By this means, the amplifier rather than the actuator link isdisplaced in the direction of arrow 111 for effecting span adjustment ofthe instrument. The virtues and simplicity of this calibration featureare otherwise preserved along the lines previously described. Moreover,by appropriately setting the height of amplifier 10 above stem 12 tomatch the operating characteristics of tube 18, linearity of theinstrument can be readily preset. The later can be effected by verticalpositioning of link 110 as by appropriately setting or adjusting thelink height prior to staking at 66.

By the above description there is disclosed a novel amplifier apparatusfor gauge instruments resolving a long standing problem with which theindustry has been plagued for many years. By virtue of its novelconstruction, the amplifier not only achieves material cost reduction ascompared to such similar purpose amplifiers of the prior art, but italso overcomes the substantial complexities of calibration difficultyand inaccurate temperature compensation characteristically typical ofsuch movements of the prior art. Consequently, the amplifier hereoffulfills a long felt need in providing a construction not previouslyregarded as possible to substantially simplify an otherwise stagnantconstruction standardized on by industry for many years. Whereas theinvention has been described principally in connection with a Bourdontube for a pressure gauge construction such description has beenutilized only for purposes of disclosure and is not intended aslimitation of the invention. To the contrary, it is to be recognizedthat the amplifier is capable of use with any condition responsiveelement producing motion in response to condition changes to which it issensitive.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the drawings and specification shall be interpreted asillustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A motion amplifier for agauge instrument having a motion producing condition responsive element,said amplifier comprising in combination:a. a support frame; b. pivotmeans pivotally supported on said support frame and including receivermeans in which to receive an actuator operably connected to thecondition responsive element for pivoting said pivot means incorrelation to the motion produced by said element; c. mounting meansadapted for mounting said support frame and said pivot means as a uniton a stationary portion of the gauge instrument; and d. calibrationmeans adjustable to displace said unit on said mounting means relativeto the received actuator for effecting presettable operational accuracyof the amplifier.
 2. A motion amplifier according to claim 1 in whichsaid receiver means comprises an elongated slot defined in said pivotmeans for receiving said actuator and said calibration means iseffective in displacing said unit to change the operational leveragebetween the actuator and said pivot means.
 3. A motion amplifieraccording to claim 2 in which said calibration means operates to effectspan adjustment of the amplifier.
 4. A motion amplifier according toclaim 1 in which said pivot means is weighted in an unbalanced relationabout its support operatively urging a weighted turning momentthereabout.
 5. A condition responsive gauge instrument comprising incombination:a. a condition responsive element producing motion inresponse to condition changes to which it is sensitive; b. actuatormeans operably connected to said condition responsive element forfloating conjoint movement therewith; c. a motion amplifier including:1.a support frame; and
 2. pivot means pivotally supported on said supportframe and including receiver means in which to receive said actuator forpivotting said pivot means in correlation to the motion produced by saidelement; d. mounting means adapted for mounting said support frame andsaid pivot means as a unit on a stationary portion of the gaugeinstrument; and e. calibration means adjustable to displace said unit onsaid mounting means relative to the received actuator for effectingpresettable calibration accuracy of the amplifier.
 6. A gauge instrumentaccording to claim 5 in which said receiver means comprises an elongatedslot defined in said pivot means for receiving said actuator and saidcalibration means is effective in displacing said unit to change theoperational leverage between the actuator and said pivot means.
 7. Agauge instrument according to claim 6 in which said calibration meansoperates to effect span adjustment of said amplifier.
 8. A gaugeinstrument according to claim 5 in which the position of said mountingmeans is selectively presettable relative to said stationary portion foreffecting linearity adjustment for said amplifier.